# 深度优先搜索
class Solution:
def isSymmetric(self, root: Optional[TreeNode]) -> bool:
if not root: # 空树
return True
def DFS(left, right):
if not (left or right): # 左右子树,都为空
return True
if not (left and right): # 左右子树,一边为空
return False
if left.val != right.val:
return False
return DFS(left.left, right.right) and DFS(left.right, right.left)
return DFS(root.left, root.right)
第五行和第七行我在想and和or是不是弄反了
还有对left和right有点疑问